Method for automatically modifying a tree structure

ABSTRACT

A method and system are provided to support automated modification to a multiple node tree structure. Each clause and each logical operator are defined in the tree structure as nodes. In addition, each link emanating from a child node to a parent node is defined as a child link, and each link emanating from a parent node to a child node is defined as a parent link. The selection and location of an operator for placement in the tree structure will be automated in response to the position selected.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to a method for modifying a logical expression. More specifically, the method automates placement of a new node to a parent node that supports at least three connecting nodes.

2. Description Of The Prior Art

Data structures in the form of trees are known as efficient tools for building tables and supporting searches beginning with a known prefix. A tree is a data structure accessed first at the root node. Each subsequent node can be either an internal node with further subsequent nodes or an external node with no further nodes existing under the node. An internal node refers to or has links to one or more descending or child nodes and is referred to as the parent of its child nodes, and external nodes are commonly referred to as leaves. The root node is usually depicted at the top of the tree structure and the external nodes are depicted at the bottom.

Tree structures are often defined by the characteristics of the tree. For example, a Binary Tree is a tree with at most two children for each node. A Digital Tree is a rooted tree where the leaves represent strings of digital symbols. The Patricia Tree is a Digital Tree with suppression of one way branching that prohibits keys which are strict prefixes of other branches. In general, a Patricia tree is always a digital tree, but only a binary tree when the symbol alphabet is binary. The internal nodes represent a common prefix to a set of strings, and each child of that node corresponds to a choice of the next symbol to follow the common prefix. A Patricia Tree can take the form of a Binary Tree and a Digital Tree where all internal nodes have at least two children.

Problems arise in adding leaves to the tree structure. In a Binary Tree where there is at most two children for each node, adding a leaf to the tree is straight forward. However, problems arise in a multiple node tree which supports more than two child nodes for each parent node. Prior art methods for modifying a tree structure that supports more than two children per node require a person to specify whether it is an operation to add a binary operator or to add a node to the tree. However, this method is time consuming as the person must select the location and operator for each child node to be added to the tree structure. Therefore, there is a need that supports automating placement of a new node in a tree structure that support more than two children per node.

SUMMARY OF THE INVENTION

This invention comprises a method and system for automating modification of a multiple node supporting tree structure based upon selection of a location for addition of a new leaf node.

In one aspect, a method is provided to amend a multiple node tree structure. A determination of a position to add a new node in the tree structure is conducted. In response to the determination, a placement of the new node to be added to the tree structure is automatically selected. The new node may be a new logical operator and/or a clause to a logical operator.

In another aspect, a system is provided with an operation manager to determine a position within a multiple node supporting tree structure for addition of a new node. An automated selection manager is also provided to automatically place the new node in the tree structure. The automated selection manager is responsive to the operation manager. The new node may be in the form of a new logical operator and/or a new clause to a logical operator.

In yet another aspect, an article is provided with a computer-readable signal-bearing medium. Means in the medium are provided for determining a position within a multiple node supporting tree structure for placement of a new node. In addition, means in the medium are provided for automatically placing the new node in the tree structure. The automatic placement means are responsive to the position determination means. The new node may be a new logical operator and/or a clause to a logical operator.

Other features and advantages of this invention will become apparent from the following detailed description of the presently preferred embodiment of the invention, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a prior art diagram of a tree structure.

FIGS. 2 a and 2 b are flow charts illustrating a process for modifying a tree structure according to the preferred embodiment of this invention, and is suggested for printing on the first page of the issued patent.

FIG. 3 is a block diagram of a modified tree structure following selection of a child link.

FIG. 4 is a block diagram of a modified tree structure following selection of a parent link.

DESCRIPTION OF THE EMBODIMENTS Overview

Automating the process of modifying a binary tree structure in the form of adding a new node to a node that can only have two child nodes is known in the art. However, in a tree structure where each node can have three or more nodes, i.e. N-ary operators, automating the process of modifying the tree structure when a new node is added becomes complicated. In one embodiment of the invention, a distinction is made between a parent node and a child node, and connections near a child node, known as a child link, and connections near a parent node, known as a parent link.

Technical Details

FIG. 1 is a block diagram (10) of a tree structure with four clauses (12), (14), (16), (18), represented as nodes, and three logical operators (20), (22), and (24). Each clause (12), (14), (16), and (18) is defined as a child node from the perspective of the logical operators (20) and (22). Similarly, each logical operator (20), (22), (24) is defined as a node, with logical operator₁ node (20) and logical operator₂ node (22) being parents nodes to clauses (12), (14), (16), and (18), and logical operator₃ node (24) being a parent node to logical operator₁ node (20) and logical operator₂ node (22). Logical operator₁ node (20) is a parent node to clause₁ (12) and clause₂ node (14), and logical operator₂ node (22) is a parent node to clause₃ node (16) and clause₄ node (18). Although both logical operator₁ node (20) and logical operator₂ node (22) are parent nodes to the defined child node, they may be defined as child nodes to logical operator₃ node (24). It is important to note that a logical operator can be a child node as well. However, in the example shown herein the logical operator nodes are parent nodes to the defined child nodes. A connection from the clause₄ node (18) to the logical operator₂ node (22) is defined as a child link (30), and a connection from clause₃ node (16) to logical operator₂ node (22) is also defined as a child link (32). Similarly, a connection from the clause₂ node (14) to logical operator₁ node (20) is defined as a child link (34), and a connection from the clause₁ node (12) to logical operator₁ node (20) is defined as child link (36). In addition to the child links as defined, parent links are the connections emanating from the parent node. A connection from logical operator₁ node (20) to child links (34) and (36) is defined as parent link (40), and a connection from logical operator₂ node (22) to child links (30) and (32) is defined as parent link (42). Accordingly, each node and each link connecting nodes are defined in the tree structure.

Once each of the elements in the tree structure are defined, modification of the tree structure may be automated. FIG. 2 is a flow chart (100) illustrating a process for automating selection and placement of a new node in a tree structure. Each clause in the tree structure is designated as a node (102), and each logical operator in the tree structure is designated as a node (104). Furthermore, each link near a child node among the links which connect a parent node and a child node, the portion of the branch, is defined as a child link (106), and each link near a parent node among the links which connect a parent node and a child node, the portion of the trunk, is defined as a parent link (108). Before initiating a change to the tree structure, a test is conducted to determine if the change requires adding a new node to the tree structure (110). A negative response to the test at step (110) is an indication that the change may be in the form of editing an existing node, whether it be one or more of the logical operators or one of more of the clauses in the tree structure. As such, the process of adding a new node to the existing tree structure ends (112). However, if the response to the test at step (110) is positive, a subsequent test is conducted to determine if the new node to be added to the tree structure is located on a child link in a multiple node supporting tree structure (114) as defined at step (106). A positive response to the test at step (114) will result in creation of a new logical operator and a new clause in the multiple node supporting tree structure (116). However, a negative response to the test at step (114) or following the completion of step (116) will result in another test to determine if the new node to be added to the tree structure is located on a parent link in a multiple node supporting tree structure (118) as define at step (108). If the response to the test at step (118) is negative, this is an indication that the modification of the tree structure does not include addition of a new node to the tree structure (120). However, a positive response to the test at step (118) will result in creation of a new clause in the form of a new child node using the logical operator type of the parent node (122). Following the creation of the new node at step (122), a final test is conducted to determine if there are any additional changes to be made to the tree structure (124). A positive response to the test at step (124) will result in a return to step (110) to determine the location and modification to be made to the tree structure. Similarly, a negative response to the test at step (124) will result in a conclusion of modifications to the tree structure (126). Accordingly, the process of determining the placement and category of a modification to a tree structure is automated based upon the specified location of the modification.

As described in FIG. 2, each clause is defined as a node and each logical operator is defined as a node. In one embodiment, the logic shown in FIG. 2 may be embodied into a tool that includes an interface to enable a user to intuitively modify a tree structure. The tool may be stored on a computer-readable medium signal-bearing medium as it is used to modify data in a machine readable format. The tool may include a requestor to determine the need for modifying the tree structure and to communicate with a manager to select the location and modification of the tree structure. The requestor and manager of the tool manager may be in the form of hardware elements within the computer system, or software elements in a computer-readable signal-bearing medium.

FIG. 3 is a block diagram (150) of the modified tree structure of FIG. 1 after editing a binary operator on child link (34). As shown, there are four original clauses (152), (154), (156), and (158), and three original logical operator nodes (160), (162) and (164). Each clause node has a child link connected to a parent link of a logical operator node. Following the process of editing the binary operator on child link (34), a new clause_(NEW) node (180) is created with a new child link (182) in communication a new parent link (184) of a new node, logical operator_(NEW) (186). Similarly, clause₁ node (152) retains child link (168) in communication with parent link (166) of logical operator₁ node (160), clause₂ node (154) obtains a new child link (170) in communication with new link (184) of a new logical operator_(NEW) node (186), clause₃ node (156) retains child link (190) in communication with parent link (194) of logical operator₂ node (162), and clause₄ node (158) retains child link (192) in communication with parent link (194) of logical operator₂ node (162). Accordingly, the process of editing a child link to add a new logical operator in a tree structure that support multiple nodes results in creation of both a new child node having a new clause and a new parent node in the form of a logical operator.

FIG. 4 is a block diagram (250) of the modified tree structure of FIG. 1 after editing a binary operator on parent link (40). As shown, there are four original clauses (252), (254), (256), and (258), and three original logical operator nodes (262), (264), and (266). Each clause node has a child link connected to a parent link of a logical operator node. Following the process of editing the binary operator on parent link (278), a new clause_(NEW) node (260) is created with a new child link (272) in communication with the original parent link (278) of logical operator₁ node (262). Similarly, clause₁ node (252) has a child link (268) in communication with parent link (278) of logical operator₁ node (262), clause₂ node (254) has a child link (270) in communication with parent link (278) of logical operator₁ node (262), clause₃ (256) has a child link (274) in communication with parent link (280) of logical operator₂ node (264), and clause₄ (258) has a child link (276) in communication with parent link (280) of logical operator₂ node (264). Accordingly, the process of editing a parent link to add a new logical operator in a tree structure that support multiple nodes results in creation of a new clause with three or more child nodes (252), (254) and (260) all in communication with parent link (278).

Advantages Over The Prior Art

The classification of each node and each connection in a multiple node supporting tree structure supports automated editing of the tree structure. Each part of a link, whether it is a child link or a parent link, performs an operation related to a nearby node. The location of the proposed change to the tree structure automatically selects the type of node to be added to the tree structure. When the link selected for editing is associated with a multiple clause operator, a new leaf may be created to the node so that the node support three or more leaves. Accordingly, the tool supports automatically editing a multiple node tree structure based upon a selection of a link within the tree structure.

Alternative Embodiments

It will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. In particular, the method and tool shown herein may be applied to a binary tree to support automated modifications to the tree structure. Accordingly, the scope of protection of this invention is limited only by the following claims and their equivalents. 

1. A method for amending a multiple node tree structure comprising: determining a position within said tree structure for adding a new node; and automatically placing said new node in said tree structure for said operation in response to said position determination, wherein said new node is selected from a group consisting of: a new logical operator and a clause to a logical operator.
 2. The method of claim 1, further comprising categorizing each clause and each logical operator in said tree structure as a node.
 3. The method of claim 2, further comprising editing said tree structure based upon said automatic selection.
 4. The method of claim 3, wherein the step of editing said tree structure includes creating a new clause node and a new logical operator node in response to editing a logical operator on a child link.
 5. The method of claim 3, wherein the step of editing said tree structure includes adding a new clause node using the operator of the parent node as a n-ary operator in response to selecting an operator on a parent link.
 6. The method of claim 5, wherein operating on a parent link is selected from a group consisting of: a binary operator and a logical operator.
 7. A system comprising: an operation manager adapted to determine a position for addition of a new node to a multiple node supporting tree structure; and an automated selection manager responsive to said operation manager adapted to automatically select a placement of said new node to be added to said tree structure for said operation in response to said determined position, wherein said new node is selected from a group consisting of: a logical operator and a clause to a logical operator.
 8. The system of claim 7, further comprising each clause and each logical operator in said tree structure categorized as a node.
 9. The system of claim 8, further comprising an editor adapted to edit said tree structure based upon said node selection by said automatic selection manager.
 10. The system of claim 9, wherein said editor amends said tree structure to include a new clause node and a new logical operator node created in response to an edit of a logical operator node on a child link.
 11. The system of claim 9, wherein said editor amends said tree structure to includes a new clause node using the operator of the parent node as a n-ary operator in response to an edit of an operator node on a parent link.
 12. The system of claim I 1, wherein said operator on a parent link is selected from a group consisting of: a binary operator and a logical operator.
 13. An article comprising: a computer-readable signal-bearing medium; means in the medium for determining a position within a multiple node supporting tree structure for placement of a new node; and means in the medium for automatically placing said new node in said tree structure in response to said position determination, wherein said new node is selected from a group consisting of: a new logical operator and a clause.
 14. The article of claim 13, wherein said medium is selected from a group consisting of: a recordable data storage medium, and a modulated carrier signal.
 15. The article of claim 13, further comprising means in the medium for categorizing each clause and each logical operator in said tree as a node.
 16. The article of claim 15, further comprising means in the medium for editing said tree structure based upon said automatic selection.
 17. The article of claim 16, wherein said means for editing said tree structure includes creating a new clause node and a new logical operator node in response to editing a logical operator on a child link.
 18. The article of claim 13, wherein said means for editing said tree structure includes adding a new clause node using the operator of the parent node as a n-ary operator in response to selecting an operator on a parent link.
 19. The article of claim 13, wherein said operator on a parent link is selected from a group consisting of: a binary operator and a logical operator. 